Metallurgical characteristics of unfluxed pellets produced from concentrates with different mineral content

The metallurgical properties of roasted unfluxed pellets are studied as a function of the maximum roasting temperature, the proportions of silica introduced by silicates and quartz, and the quantity and composition of glassy silicate binder in the pellets. The mineral formation in the thermal strengthening of unfluxed pellets produced from concentrates with different mineral composition is analyzed. The microstructure of the final pellets is described.     

New Boolean Equation for Orthogonalizing of Disjunctive Normal Form based on the Method of Orthogonalizing Difference-Building

In this paper a new Boolean equation for the orthogonalization of Boolean functions respectively of Ternary-Vector-Lists of disjunctive normal form is presented. It provides the mathematical solution of orthogonalization for the first time. The new equation is based on the new method of orthogonalizing difference-building ?. In contrast to other methods the new method has a faster computation time. Another advantage is the smaller number of product terms respectively of Ternary-Vectors in the orthogonalized result in contrast to other methods. Furthermore, the new equation can be used as a part in the calculation procedure of getting suitable test patterns for combinatorial circuits for verifying feasible logical faults.     

Influence of the reactivity of coke on blast-furnace performance

The cold strength M ₂₅₍₄₀₎ and M ₁₀ of the coke determines the gas permeability of the batch bed in the blast furnace down to the viscoplastic zone of the ore and the coke windows in that zone. The hot characteristics CRI and CSR determine the mechanical strength of the coke in the lower part of the furnace batch, in and below the viscoplastic zone, including the furnace well. It is wrong to regard the hot and cold characteristics as alternatives, since they describe different conditions; the significance of each one should be acknowledged. The coke consumption may be reduced with increase in reactivity of the coke, so long as the high initial strength of the coke is maintained. The minimum permissible reactivity of the coke without clogging of the hearth depends on the operating conditions in the specific blast furnace.     

Cathodic electrodeposition of SnS in the presence of EDTA in aqueous media

Cathodic electrodeposition in the presence of EDTA in aqueous solution was found to offer some noteworthy improvements in our attempt to synthesise an SnS thin film. EDTA has shown its capacity for improving the longevity of the deposition bath as well as the adhesion of the deposited film on a titanium substrate. Photoelectrochemical analysis reveals outstanding photoactivity of the electrodeposited thin film, while an optical study shows an energy gap of approximately 1.1 eV. The effects of chelating agent were extracted from the results of cyclic voltammetry, photoelectrochemical test, scanning electron microscopy and X-ray diffraction spectroscopy. The latter which displays better defined signals reaffirms the appreciable improvement in the polycrystallinity of the thin film. Analysis of peak locations, coincidentally, confirms that SnS of Herzenbergite form has been obtained.     

Studies on reduction of chromium doped iron oxide catalyst using hydrogen and various concentration of carbon monoxide

Chemical reduction behaviour of 3% chromium doped (Cr–Fe₂O₃) and undoped iron oxides (Fe₂O₃) were investigated by using temperature programmed reduction (TPR). The reduced phases were characterized by X-ray diffraction spectroscopy (XRD). The reduction processes were achieved with 10% H₂ in nitrogen (%, v/v), 10% and 20% of carbon monoxide (CO) in nitrogen (%, v/v). In hydrogen atmosphere, the TPR results indicate that the reduction of Cr–Fe₂O₃ and Fe₂O₃ proceed in three steps (Fe₂O₃ → Fe₃O₄ → FeO → Fe) with Fe₃O₄ and FeO as intermediate states. A complete reduction to metallic iron for both samples occurred at 900 °C. As for CO reductant, the profiles show the reduction of Fe₂O₃ also proceeded in three steps with a complete reduction occurs at 900 °C in 10% CO with no sign of carbide formation. Nevertheless, a 20% CO was able to reduce the completely at lower temperature at 700 °C and there is a formation of iron carbide at 500 °C but the carbide disappeared as the reduction temperature increase. Meanwhile in 10% CO atmosphere, Cr–Fe₂O₃ shows a better reducibility compared to Fe₂O₃ with a complete reduction at 700 °C, which is 200 °C lower than Fe₂O₃. A Cr dopant in the Fe₂O₃ can lead to formation of various forms of iron carbides such as F₂C, Fe₅C₂, Fe₂₃C₆ and Fe₃C as the CO concentration was increased to 20%. The transformation profile of iron phases during carburization follows the following forms, Fe₂O₃ → Fe₃O₄ → iron carbides (Fe_xC). The XRD pattern shows the diffraction peaks of Cr–Fe₂O₃ are more intense with improved crystallinity for the characteristic peaks of Fe₂O₃ compare to undoped Fe₂O₃. No visible sign of chromium particles peaks in the XRD spectrum that indicates the Cr particles loaded onto the iron oxide are well dispersed. The uniform dispersion with no sign of sintering effects of the Cr dopant on the Fe₂O₃ was confirmed by FESEM. The study shows that Cr dopant gives a better reducibility of iron oxide but promotes the formation of carbides in an excess CO concentration.     

Reducing burn-in time through high-voltage stress test and Weibull statistical analysis

To guarantee an industry standard of reliability in ICs, manufacturers incorporate special testing techniques into the circuit manufacturing process. For most electronic devices, the specific reliability required is quite high, often producing a lifespan of several years. Testing such devices for reliability under normal operating conditions would require a very long period of time to gather the data necessary for modeling the device's failure characteristics. Under this scenario, a device might become obsolete by the time the manufacturer could guarantee its reliability. High-voltage stress testing (HVST) is common in IC manufacturing, but publications comparing it with other test and burn-in methods are scarce. This article shows that the use of HVST can dramatically reduce the amount of required burn-in.